Case: A 42-year-old male comes in complaining of neck pain and difficulty moving his upper extremities after trauma. The patient was involved in a motor vehicle collision where he was in the front passenger seat and was hit from that side. The patient had a loss of consciousness and complains of nausea, headache, vomiting, and trouble with motor function of his arms. He also complains of decreased sensation.

On exam, the patient has decreased sensation of bilateral upper extremities as well as 3 out of 5 strength in his upper extremities. What is the best method to immobilize the patient’s spine?

Introduction: A few months ago we covered an article considering the evidence and myths surrounding the pre-hospital use of the long backboard for spinal immobilization in trauma patients with suspected spinal cord injuries (http://www.emdocs.net/pre-hospital-management-of-spinal-injuries-debunking-the-myths-of-the-long-backboard/). This time, we will consider the utility of another device reflexively applied to these patients – the rigid cervical collar. From the NAEMT to PHTLS and ATLS, c-spine stabilization is considered a major priority after the ABCs. Pre-hospital EMS protocols dictate that whenever a patient admits to neck pain or any neurological symptoms following trauma, applying a rigid plastic, often ill-fitting, uncomfortable cervical collar is mandatory. The purpose of these devices is to prevent further motion of the cervical spine by maintaining in-line stabilization that could theoretically worsen a c-spine injury, convert a partially unstable fracture into an unstable fracture or a convert a partial spinal cord injury into a complete spinal cord transection. This bears us to ask the question – what evidence exists to support the use of these devices?

Can small voluntary spinal movements cause harm?

There is a fear that any movement of the cervical spine will cause further injury or worsen already existing spinal fractures or injury; however, there is no evidence that slight movement of the cervical spine will cause worsening injury. Maiman et al performed a study on cadavers involving applying forces to their necks vertically, forward and rearward to attempt to cause ligamentous injury and fracture. The loads required to cause an injury ranged from 645 to 7,439 Newtons of force.1 This study sets precedent that it may not be movement of the spine, but the force from a strong impact that causes injury. Therefore, the fear of movement, such as minimal head turning, flexion and extension of the cervical spine, or movement during airway management causing worsening injury appears to be somewhat unfounded.

Do cervical collars truly immobilize the cervical spine?

Again, we can turn to cadaver studies as well as biomechanical analysis of live patients during extrications to answer this question. Horodyski et al tested axes of cervical motion in all planes in lightly embalmed cadavers both with an intact c-spine and induced global instability at C5-C6. Motion was tested in five cadavers using EMG sensors applied to the C5-C6 vertebral bodies, comparing no collar, to a one-piece extrication collar (Ambu), and two-piece (Aspen) collar in repeated measures. The results of this study indicated that though significantly more motion occurred in the unstable cadaver c-spine, no significant difference in motion occurred with the application of either cervical collar compared to the no intervention group. Even more surprising, a similar cadaver study with induced unstable C-spine fractures by Lador et al documented increased intervertebral motion in both the axial and cranial-caudal planes in the one-piece rigid collar group compared to no intervention as well as the creation of a “pivot point” of enhanced motion where the collar contacts the TMJ and shoulder areas (we will mention this later).2 Finally, a study by Dixon et al extricating healthy volunteers from a simulated motor vehicle crash in a RCT comparing conventional equipment and manual aided techniques including the cervical collar showed four times as much motion using equipment as opposed to controlled self-extrication with no collar.3

Does the cervical collar positively affect the neurological outcomes of patients with spinal cord injuries?

There are no prospective, randomized patient studies that look at the use of cervical collars versus placebo. Hauswald et al. performed a retrospective cohort study comparing blunt trauma patients in two different systems, the United States (which routinely immobilizes patients) and Malaysia (which does not routinely immobilize patients). They compared patients with and without spinal immobilization and performed multivariate logistic regression analyses. They found that there was less neurologic disability in the unimmobilized patients from Malaysia (OR 2.03, 95% CI 1.03-3.99; p=0.04).4 This supports the possibility that immobilization may actually be harmful.

Can cervical collars cause further harm to the trauma patient?

C-collars can potentially increase intracranial pressure. Stone et al. took healthy volunteers and placed them in cervical collars. Their internal jugular vein cross-sectional area was measured before and after cervical collar application, and showed a mean percentage increase of 37% with the collar applied.5 Theoretically, the decreased venous return may increase intracranial pressure, which is something we want to avoid in patients with intracranial injury.

The neck pivot-shift phenomenon was demonstrated by Lador et al. in a study performed on cadavers. Intervertebral movements were measured based on CT imaging after application of cervical collars. It was found that “pivot points” shifted the center of rotation lateral to the spine and worsened motion between vertebrae. These points can cause stress on the c-spine due to the use of the collar.

The cervical collar can lead to increased intracranial pressure. A prospective study found that CSF pressure increased by approximately 25 mm H20 in a group pre- and post c-collar application in patients undergoing lumbar puncture.6

Based on the available data, it does not appear that cervical collars have any appreciable positive effect on patient care. However, at this point in time, they are the recommended treatment option. Hopefully this knowledge will help your daily practice by understanding the effects of cervical immobilization.

Case Resolution: The patient is carefully placed into a rigid, padded collar and asked not to move his neck in any direction. He undergoes appropriate imaging and management per the trauma and spinal surgery teams.

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